The invention relates to an electric machine and to a method for operating an electric machine.
The use of coils made of a superconducting material in a rotor of an electric machine is known in the art. Thus, the published patent application DE 10 2004 04 754 A1, for example, describes a rectangular coil made of strip-shaped superconductors for use in an electric machine.
As a rule, these superconducting coils must be supplied with an electric current continuously during operation of the electric machine so that they generate a rotor magnetic field in the rotor. If the electric current is switched off, the corresponding rotor magnetic field also disappears.